...Mr. Montgomery and his associates received more than $20 million in government contracts by claiming that software he had developed could help stop Al Qaeda’s next attack on the United States. But the technology appears to have been a hoax, and a series of government agencies, including the Central Intelligence Agency and the Air Force, repeatedly missed the warning signs, the records and interviews show.

Mr. Montgomery’s former lawyer, Michael Flynn — who now describes Mr. Montgomery as a “con man” — says he believes that the administration has been shutting off scrutiny of Mr. Montgomery’s business for fear of revealing that the government has been duped.